Gyroidina

Gyroidina is a genus of benthic foraminifera belonging to the family Gavelinellidae. These are single-celled organisms with a calcareous test (shell) characterized by its trochospiral or plano-convex shape. The test is typically composed of multiple chambers arranged in a spiral, with a distinct umbilical side and a spiral side.

Gyroidina species are commonly found in marine environments, from shallow shelf areas to deep-sea settings. They are an important component of benthic communities and contribute significantly to the marine carbonate budget. Their fossil record extends back to the Cretaceous period, making them useful for biostratigraphy and paleoenvironmental reconstruction.

Distinguishing features of Gyroidina include their smooth or slightly ornamented test surface, radial sutures between chambers, and a relatively wide umbilicus. The aperture is typically a slit-like opening located at the base of the final chamber, extending along the umbilical suture.

Different species within the genus Gyroidina are differentiated based on variations in test morphology, such as the number of chambers, the shape of the spiral and umbilical sides, the ornamentation of the test surface, and the characteristics of the aperture.

The ecological preferences of Gyroidina species vary, with some species being tolerant of low-oxygen conditions, while others require well-oxygenated environments. The distribution and abundance of Gyroidina species can therefore provide valuable insights into past and present oceanographic conditions.